X∼B(50,0.4). Use a normal approximation to find P(X≥25), correct to 3 significant figures.
Salam Academy Original Practice · Proposed mark scheme
SA-MOM-0044 marksL3 ExamCalculatorTilting
A uniform plank AB, 6 m long and of mass 20 kg, rests on supports at C and D, where AC=DB=1 m. A man of mass 70 kg walks from D towards B. Find his distance from A when the plank is about to tilt, to 3 significant figures.
Salam Academy Original Practice · Proposed mark scheme
In the proof above, the case n=3k+2 gives n2=9k2+12k+4=3(3k2+4k+1)+r. Find r.
Salam Academy Original Practice · Proposed mark scheme
SA-PX-EY-0032 marksL3 ExamCalculatorDefects
A long-sighted person has a near point of 1.0 m. Calculate the power of lens that lets them read a book at 0.25 m.
Salam Academy Original Practice · Proposed mark scheme
SA-PX-VI-0033 marksL3 ExamCalculatorStokes’ law
A steel ball of radius 1.0 mm and density 7800 kg m⁻³ falls through glycerol of density 1260 kg m⁻³ and viscosity 1.4 Pa s. Calculate its terminal velocity in cm s⁻¹.
Salam Academy Original Practice · Proposed mark scheme
SA-ST-PG-0033 marksL3 ExamNon-calculatorMoments
For G(t)=41(1+2t+t2), find Var(X).
Salam Academy Original Practice · Proposed mark scheme
Lines l1 and l2 have equations r=2−10+λ121 and r=044+μ1−1−1. Show that the lines intersect and find the coordinates of the point of intersection.
Salam Academy Original Practice · Proposed mark scheme